Electron beam recording material

ABSTRACT

WHEREIN R is a phenyl or naphthyl group which may be substituted by a hydrogen atom, a halogen atom or an alkyl or alkoxyl group having 1 to 4 carbon atoms.   A highly sensitive electron beam recording material is obtained by adding to the system of N-vinylcarbazole and tetrabromomethane in a hydrophilic binder an additive of a leucomethylene blue having the formula

United States Patent 1191 Hashiue et al.

1451 Feb. 5, 1974 i 1 ELECTRON BEAM RECORDING MATERIAL [73] Assignee: Fuji Photo Film Co., Ltd., Minami Ashigara-shi, Kanagawa, Japan [22] Filed: Sept. 3, 1971 [21] Appl. No.: 177,761

[30] Foreign Application Priority Data Sept. 3, 1970 Japan 45-77408 52 US. c1. 96/27 R, 96/90 R, 117/368, 117/155 UA 51 Int. Cl G03c 5/04 58 Field of Search 96/1.5, 1.6, 90 R, 27 R; 117/362, 36.8

[56] References Cited UNITED STATES PATENTS 3,525,616 8/1970 l-lackman et al 96/90 R 3,l47,l 17

9/1964 Wainer et al. 96/90 R Sprague et al. 96/90 R Fotland 96/90 R Primary Examiner-Murray Katz Attorney, Agent, or Firm-Sughrue, Rothwell, Mion, Zinn and Macpeak [5 7] ABSTRACT A highly sensitive electron beam recording material is obtained by adding to the system of N-vinylcarbazole and tetrabromornethane in a hydrophilic binder an additive of a leucomethylene blue having the formula CH3 S /CH:1

\N N\ 0 CH;

alkyl or alkoxyl group having 1 to 4 carbon atoms.

3 Claims, 1 Drawing Figure ELECTRON BEAM RECORDING MATERIAL BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recording material suitable for directly recording image information by electron beam, that is, a material for recording an electron beam having high sensivity which is easily treated.

2. Description of the Prior Art Recording of image information using electron beams has been employed in the field of electron microscopic photography. This way of recording is also employed to record information in an electron beam drawing apparatus and for the direct recording of output information of a computer on a recording material which is placed, instead of a phosphorescent screen, in a cathode ray tube. This way of recording has recently become quite important.

Therefore, in the process for recording images on a recording material using an electron beam, a recording material having a high sensitivity to the electron beam is required. If the electron beam sensitivity of the recording material is low, defects in the convergence of the electron beam, in the accumulation of electric charge and in the writing-in rate occur. If the electron beam sensitivity of a recording material is low, an electron beam having a high electronic current density is required. When recording an image by a scanning electron beam focused into a small spot on a recording material with an electron beam having a large electric current it is difficult to focus into a microscopic spot and, accordingly, it is not suitable for recording of high density information. If the electronic current density is high, the electric charge of the incident electrons accumulates on the recording material to deteriorate the image quality.

Furthermore, when electron beam recording is conducted at a given electronic current density, the lower the electron beam sensitivity of the material is, the longer time of exposure is required and, accordingly, the writing-in rate lowers.

As is obvious from the description above, it can be seen that in the process for recording images on a recording material by using an electron beam, a recording material having high sensitivity to the electron beam is necessary.

It should be noted that, in preparing such recording material having a high sensitivity to an electron beam, the process for raising the sensitivity to light cannot be applied as such.

In other words, it isnot rare that a material havinghigh sensitivity to light has'a conspicuously low sensitivity to an electron beam and that the order of sensitivity to light and electron beam reverses. For example, the sensitivity of Neopan SS, a highly light sensitive negative film, made by Fuji Photo Film Co., Ltd., is times that of Type ST, an electron microscopic film made by Fuji Photo Film Co., Ltd., when subjected to an exposure amount which gives a photographic density (base density fog density) of 0.3. However, to a 50 KV electron beam, the latter has a high sensitivity reversely of about 5 times that of the former.

For another example, it has been ascertained by our experiments that Kalvar film (made by Kalvar Corp.) has a photosensitivity several times that of a diazo sensitive material (made by Ricoh Company Ltd.) but, reversely, has a sensitivity to a 60 KV electron beam of half the latter.

There is also a description reported by A. Shepp ct al, in Photographic Science and Engineering," Volume ll, page 322( 1967) about the failure of a corresponding relation between photosensitivity and electron beam sensitivity.

Such results are also obvious from the fact that a photochemical change is caused on a recording material by photons which are the nature of light and this is quite different in character from the change caused on the recording material by accelerated electrons which are the nature of an electron beam.

The differences between photons (within the region of from ultraviolet to visible region) and accelerated electrons are as follows:

l The former do not have electric charge, while the latter have it.

2. The energy carried by the former is only several electron volts, while the energy carried by the latter can be raised according to the accelerating voltage and, within the usually used region thereof, it is in the range of from several kiloelectron volts to several ten kiloelectron volts.

Accordingly, it is rather quite natural that a complete corresponding relation fails between photosensitivity and electron sensitivity of a material because of the presence or absence of electric charge and the wide difference in energy thereof.

Therefore, thesearch for a material with a high sensitivity to an electron beam must be made from a standpoint quite different from that for a search for a material with a high photosensitivity.

As a recording material for electron beams, silver halidegelatin photographic emulsion has been used widely so far. It is truethat this kind of recording material has high sensitivity to electron beams, but they have such defects that photographic treatment thereof is by a wet process and troublesome. There are other recording materials made of diazo compounds or those of drysilver process and the like used for electron beam recording whose treatments are of dry process and simple. However, these materials have such a defeet as is known widely, that they all have low sensitivity when compared with the recording materials using a silver halide-gelatin photographic emulsion.

In the book Light Sensitive Systems John Wiley & Sons, Inc. 1965) written by J. Kosar, at page 369, there is a description about the fact that the system of N-vinylcarbazole and tetrabromomethane has a sensitivity to electron beams, but, as will be described in detail hereinafter, the sensitivity thereof is quitelow compared with that of silverhalide-gelatin photographic emulsion.

SUMMARY OF THE lNVENTlON r We have succeeded, after various kinds of investigation, in raising the sensitivity of the system of N- vinylcarbazole and tetrabromomethane to electron beams by ID times by adding, as will be described in detail hereinafter, a hydrophilic binder having a filmforming ability together with a suitable additive to the system, whose sensitivity is as much as or more than that of the sensitive material using a silver halidegelatin photographic emulsion. In this case, a significant rise insensitivity to visible light cannot be observed.

The term hydrophilic binder having a filmforming ability. means gelatin, polyvinyl alcohol. carboxymethyl cellulose, starch, casein, gum arabic, hydroxyethyl cellulose, polyvinyl pyrrolidone and the like.

The term additive means non-substituted or substituted benzoyl or naphthoyl leucomethylene blue having the following general formula:

CH3 5 I I 21:0 it I wherein R represents a phenyl or naphthyl group which may be substituted by a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms or an alkoxy group having I to 4 carbon atoms.

DESCRIPTION OF THE PREFERRED,

EMBODIMENTS A weight ratio of leucomethylene blue to N- vinylcarbazole is l/l00,000 to 1/10, more preferably l/l0.000 to l/l,0O0.

The weight ratio of tetrabromomethane to N- vinylcarbazole is l/5O to 50 more preferably l/5 to 5.

The weight ratio offilm-forming polymer to the sum of N-vinylcarbazole and tetrabromomethane is H100 to and more preferably, l/lO to 20. As a support for the recording material a conventional photographic support is used such as baryta paper, resin-coated paper, cellulose acetate film, polyethylene terephthalate film and the like.

The present invention will be further explained by the following Examples.

EXAMPLE 1 4 g. of gelatin was swollen in 1-5 ml of water and dissolved at 40-50 C. 2.5 g, of N-vinylcarbazole were then added and stirred at a high spped using a homogenizer at atem e enas C t al ixenq it perselThereafter, 2.5 g. of tetrabromomethane and 3 mg. of benzoyl leucomethylene blue were added and again in the same way emulsified and dispersed to prepare an emulsion. The resulting emulsion was coated onto baryta paper used for photography with a rod and dried at room temperature ina dark place to prepare a recording material.

The recording material thus obtained was placed inside an electron microscope at the position for the sensitive materal. The electron microscope had an accelerating voltage of KV and the material was then irradiated with the electron beam. The term the-position for the sensitive material means the position where the photographic film or the photographic dry plate is placed when usually taking an electron microscopephotograph. The electron beam intensity was changed within the range of from l X 10 ampere/cm to l X l0" amphere/cm The time of exposure was changed within the range of from I to 100 seconds.

After irradiating with the electron beam in the way described above, the recording material was immediately taken out of the electron microscope and exposed to a 300 watt flood lamp through a red filter (which transmits light of wavelength longer than about 600 mu) for 2 seconds at a distance of 40 cm. from the lamp. This recording material was then kept at a temperature of C for about 10 seconds.

In the FIGURE, the characteristic curve of the response of this recording material to the irradiation with the electron beam is given by curve No. 1. In the FIG- URE, the amount of the irradiation by the electron beam (in units of coulomb/em isplotted as the abscissa and the visual reflection density as the ordinate.

All the operations, from the preparation of the recording material to the sensitometry for electron beam exposure, were carried out under a red safety lamp for photographic use.

This red safety lamp is a 20 watt tungsten electric lamp covered with Fuji safe light glass No. 2B, which is kept away at a distance of more than 1.5 m. during the operation.

The above-mentioned operation was conducted on the prepared materials and the same operation was d cineifithe following Examples 2-4.

EXAMPLE 2 Co., Ltd.) instead of geltain to prepare a recording material which was treated in the similar way.

EXAMPLE 4 The procedure d e s eribed in Example I was carried out using 3.2 mg. of the additive naphthoyl leucomethylene blue instead of 3 mg. of benzoyl leucomethylene blue to prepare a recording material which was treated in the similar way.

Using these recording materials prepared by Examples l-4, similar results wereobtained as is described hereafter.

The present invention will be further explained by the following comparison examples.

COMPARISON EXAMPLE 1 A recording material which consists of N- vinylcarbazole and tetrabromomethane and which uses gelatin as a binder was prepared according to the procedure described in Example 1 without adding the additive benzoyl leucomethylene blue.

That is, the recording material was prepared in the following way. 4 g. of gelatin were swollen in 15 ml of water and heated to 40-50 C to dissolve. 2.5 g. of N- vinylcarbazole were then added and stirred at a high speed using a homogenizer at a temperature of 70-72" C to emulsify and disperse. Thereafter, 2.5 g. of tetrabromomethane were added and again in the same way emulsified and dispersed to prepare an emulsion. The resulting emulsion was coated onto baryta paper used for photography with a rod and dried at room temperature in a dark place to prepare the recording material.

The characteristic curve which shows the response of the recording material obtained byComparison Example l to 50 KV electron beam is-given by curve No. 2 in the FIGURE. The manner of the irradiation with the electron beam and the treatment thereafter are the same as in Example 1.

COMPARISON EXAMPLE 2 The procedure described in Comparison ExampleT was carried out using polyvinyl alchohol (GOHENOL GL-03, made by The Nippon Synthetic Chemical Industry Co., Ltd.) instead of gelatin to prepare a recording material. The response characteristics of there: cording material prepared by Comparison Example 2 with respect to the electron beam are about the same as that of the recording material prepared by Comparison Example 1, but the sensitivity of the former is about ten times that of the latter.

COMPARISON EXAMPLE 3 Among recording materialsusing a gelatin photographic emulsion, the characteristic curve of MINI- COPY film (made by Fuji Photo Film Co., Ltd. emulsion number 77534-348-05) in the irradiation with the electron beam is given by curve No. 3 in the FIGURE. For this case only, the visual diffuse transmission density was plotted as the ordinate. The irradiation condition of the electron beam was that the accelerating voltage was 50 KV, the electron beam intensity on the Mctol (Monol) 1.0 g. Anhydrous sodium sulfite 75.0 g. Hydroquinone 9.0 g. Sodium carbonate H O 29.0 g. Potassium bromide 6.0 g.

per liter of FD-l3l treating solution.

As is obvious from the FIGURE, the sensitivity of the system of N-vinyl carbazole and tetrabromomethane to which no additive was added wasfar lqwer than that of MINOCOPY film (Comparison Example 1). The photographic density obtained by the former was also low.

We have succeeded in raising the sensitivity to times that of the system of N-vinyl carbazole and tetrabromomethane without an additive by adding a suitable additive to the same system. As a result, the sensitivity of the system of N-vinyl carbazole and tetrabromomethane using an additive is improved to a sensitivity as high as or higher than that ofa recording material using a silver halide-gelatin photographic emulsion.

The heating treatment of C for 10 seconds of this recording material in Example I, which was doneafter the irradiation with the electron beam and the exposure with a red light, could be replaced by an exposure to ultraviolet light.

The exposure with ultraviolet light was carried out by using a Uniarc, made by Ushio Denki Co., Ltd. as a source of ultraviolet light by placing the sample at a distance of about 70 cm. from the mercury lamp and exposing it for 10 seconds.

The recording material prepared by this invention has the advantages that it has a high sensitivity to an electron beam and that the subsequent treatment thereof is a completely dry process.

What we claim is: v

1. An electron beam recording material having a high sensitivity to electron beams comprising a support having thereon a layer consisting essentially of a hydrophilic film-forming polymer binder, N-vinylcarbazole, tetrabromomethane and leucomethylene blue having the following formula:

wherein R is selected from the group consisting of a phenol group and a naphthyl group wherein each may be substituted by a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms or an alkoxyl group having 1 to 4 carbon'atoms wherein the weight ratio leucomethylene blue/N-vinylcarbazole varies from l/l000 to l/lO; wherein the weight ratio tetrabromomethane/N-vinylcarbazole varies from l/50 to 50/1 and wherein the weight ratio hydrophilic film-forming polymer binder/sum of N-vinylcarbazole and tetrabromomethane varies from l/lOO to 20/1.

2. An electron beam recording material as claimed in claim 1 wherein said hydrophilic film-forming polymer binder is selected from the group consisting of gelatin, polyvinyl alcohol, carboxymethyl cellulose, starch casein, gum arabic, hydroxyethyl cellulose and polyvinyl pyrrolidone.

3. An electron beam recording material as claimed in claim 1 where said support is selected from the group consisting of baryta paper, resin-coated paper, cellulose acetate film and polyethylene terephthalate film. 

2. An electron beam recording material as claimed in claim 1 wherein said hydrophilic film-forming polymer binder is selected from the group consisting of gelatin, polyvinyl alcohol, carboxymethyl cellulose, starch, casein, gum arabic, hydroxyethyl cellulose and polyvinyl pyrrolidone.
 3. An electron beam recording material as claimed in claim 1 where said support is selected from the group consisting of baryta paper, resin-coated paper, cellulose acetate film and polyethylene terephthalate film. 